The invention relates to an electronic interface device which takes input from two electronic devices and permits the user to select which input is fed to a display screen.
Many kinds of electronic devices for use by individuals are known, such as notebook or laptop computers, personal digital assistants (PDAs) and mobile telephones. Notebook computers are designed as general purpose computing platforms, and as such include relatively large display screens and powerful multimedia computing capabilities. The multimedia computing requires a dedicated graphics processor that consumes high levels of power. Smaller application specific electronic devices such as PDAs and mobile telephones do not usually require multimedia capabilities and therefore have much smaller display screens. Low power simplified graphics processors are therefore suitable for such devices, with the advantage that the devices consume much lower levels of power, providing for much longer battery life and the use of smaller battery packs.
The small display screens on the smaller electronic devices, whilst adequate for many PIM applications, are however not ideal for all uses of such devices, for example for web browsing and note taking applications. Hence the ability to use the larger screen of the notebook computer to display the output of the smaller electronic device would in some circumstances be advantageous, and it is an object of the present invention to provide this new facility.
According to the present invention there is provided an electronic interface device characterised in that it has a first input for the receipt of signals from a graphics controller of a first electronic device having a display screen, and a second input for the receipt of signals from a second electronic device, a multiplexer, an output to the display screen of the first electronic device and switch means to select which input signal is fed to the display screen via the output.
The invention provides the advantage that the display screen of the first electronic device can be employed, to display the output from the second electronic device, without any assistance from the microprocessor or graphics controller of the first electronic device, hence saving power.
In one embodiment the electronic interface further includes a receiver, connected between the first input and the multiplexer, for conversion of input signals received from the graphics controller of the first electronic device in a first format into a second format, and a transmitter, connected between the multiplexer and the output, for conversion of the selected output signal to the first format, wherein the second input signal is received in the second format and the multiplexer operates on signals in the second format.
In an alternative embodiment the electronic interface device further includes a transmitter, connected between the second input and the multiplexer, for conversion into a first format of the input signal received from the second electronic device in a second format, wherein the first input signal is received in the first format and the multiplexer operates on signals in the first format.
Conveniently the first signal format is LVDS and the second signal format is FPL.
The electronic interface device may conveniently be implemented on a mixed signal FPGA.
The switch means within the electronic interface device is preferably implemented in software.
The electronic interface device may conveniently be implemented integrally with the first electronic device.